Energy that powers our world
Electricity lights our homes, runs our devices and charges our phones. It’s energy carried by moving electric charges. Lightning, a spark from a doorknob and the signals in your nerves are all forms of electricity.
Electric charge
All matter is made of atoms, which contain:
- protons with a positive (+) electric charge
- electrons with a negative (−) charge
- neutrons with no charge
Rules of charge:
- Like charges repel (push apart).
- Opposite charges attract (pull together).
Static electricity
Static electricity is a build-up of charge on the surface of an object. When you rub two materials together, electrons can move from one to the other.
- Rub a balloon on your hair: electrons move to the balloon. The balloon becomes negative, your hair positive, and they attract.
- Your hair stands up because each strand has the same charge and they repel each other.
- A shock from a doorknob happens when built-up charge jumps to the metal.
Lightning is a giant static spark. Charges build up in storm clouds, then jump to the ground or another cloud. A lightning bolt can heat the air to about 30 000 °C, hotter than the Sun’s surface. The rapidly expanding air makes thunder.
Current electricity
Electric current is a steady flow of electric charge, like water flowing through a pipe.
| Term | Meaning | Unit | Water analogy |
|---|---|---|---|
| Current | How much charge flows each second | Ampere (A) | How much water flows |
| Voltage | The push behind the charge | Volt (V) | Water pressure |
| Resistance | How much a material slows the flow | Ohm (Ω) | A narrow pipe |
Ohm’s law connects them: voltage = current × resistance.
Circuits
Electricity flows only around a complete loop called a circuit.
A simple circuit has:
- an energy source (battery)
- wires
- a load (bulb, motor or buzzer)
- often a switch
| Series circuit | Parallel circuit |
|---|---|
| One path | Several paths |
| If one bulb breaks, all go out | Others stay on |
| Adding bulbs makes each dimmer | Bulbs stay bright |
Homes are wired in parallel so each light and appliance works independently.
Conductors and insulators
| Conductors | Insulators |
|---|---|
| Let electricity flow easily | Block electricity |
| Copper, aluminum, gold, salt water | Rubber, plastic, glass, dry wood |
Wires are made of copper covered in plastic insulation.
Where electricity comes from
Most electricity is made by generators. Spinning a coil of wire near magnets (or magnets near a coil) creates an electric current. Something has to spin the generator:
| Source | What spins the generator |
|---|---|
| Hydroelectric dams | Falling water |
| Wind turbines | Wind |
| Coal, gas and nuclear plants | Steam from heated water |
Solar panels work differently: they turn sunlight directly into electricity.
Batteries store chemical energy and release it as electricity.
In Canada, about 60% of electricity comes from hydroelectric power. Quebec, Manitoba, British Columbia and Newfoundland and Labrador produce most of their electricity from water.
AC and DC
- Direct current (DC) flows in one direction. Batteries and solar panels produce DC.
- Alternating current (AC) switches direction many times a second. Wall outlets in North America supply AC at 120 volts and 60 times a second (60 Hz).
Electrical safety
- Never touch outlets or wires with wet hands.
- Don’t overload outlets with too many plugs.
- Stay far away from downed power lines.
- Never fly kites near power lines.
- In a thunderstorm, go indoors. "When thunder roars, go indoors."
Saving electricity
Turn off lights, unplug chargers, use LED bulbs and choose energy-efficient appliances. Saving electricity saves money and reduces pollution.
Common mistakes
- Thinking electricity is used up in a bulb. The charges keep flowing; their energy is changed to light and heat.
- Thinking batteries store electricity. They store chemical energy.
- Thinking rubber shoes make you safe from lightning.
Try it yourself
- Rub a balloon on your hair and hold it near small bits of paper. Explain what happens.
- Build a circuit with a battery, a bulb and wires. Add a switch made from a paper clip.
- Make a lemon battery: push a copper coin and a galvanized nail into a lemon and connect them to a small LED.
Quick recap
- Electricity is energy carried by moving charges.
- Static electricity is built-up charge; lightning is a giant spark.
- Current flows around a complete circuit, pushed by voltage.
- Conductors carry electricity; insulators block it.
- Generators turn motion into electricity; batteries store chemical energy.